1. Field of the Invention
The present invention relates generally to supports for holding a stent, and more particularly, but not exclusively, relates to devices for holding a stent during manufacturing processing such as electropolishing or spray coating the stent with a beneficial agent or other coating.
2. Background of the Invention
Stents, grafts and a variety of other endoprosthesis are well known and used in interventional procedures, such as for treating aneurysms, for lining or repairing vessel walls, for filtering or controlling fluid flow, and for expanding or scaffolding occluded or collapsed vessels. Such endoprosthesis can be delivered and used in virtually any accessible body lumen of a human or animal, and can be deployed by any variety of recognized means. One recognized indication of endoprosthesis, such as stents, is for the treatment of aetherosclerotic stenosis in blood vessels. For example, after a patient undergoes a percutaneous transluminal coronary angioplasty or similar interventional procedure, an endoprosthesis, such as a stent, is often deployed at the treatment site to improve the results of the medical procedure and to reduce the likelihood of restenosis. The endoprosthesis is configured to scaffold or support the treated blood vessel; if desired, the endoprosthesis can also be loaded with beneficial agent so as to act as a delivery platform to reduce restenosis or the like.
Generally there are two distinct types of endoprosthesis, balloon expandable and self-expanding endoprosthesis. A balloon expandable endoprosthesis is generally constructed of materials such as stainless steel, cobalt chromium or some blend thereof, wherein the stent is crimped onto a balloon for delivery into a vessel or artery. The stent may be plastically deformed when crimped onto the balloon and then plastically deformed when the balloon is expanded to deploy the prosthesis. Generally balloon-expandable stents are cut from tubes and then undergo various manufacturing processes to become a finished product.
Self-expanding stents are generally fabricated from metals having superelastic properties, wherein the stent pattern is cut into a tube, wherein the cut tube undergoes a series of manufacturing steps to become a finished product.
Typically after the stent pattern has been cut into the wall of the tubing to form the stent, the stent is blasted with media to remove burs, slag and other manufacturing byproducts. After blasting, the stents are generally electropolished to create a smooth surface along the length of the stent as well as along the cut edges of the stent. During the electropolishing step, the stents are generally mounted on a mandrel and submerged in a chemical bath to perform the polishing process as described in U.S. patent application Ser. No. 11/370,660, filed Mar. 7, 2006, now U.S. Pat. No. 8,038,803, entitled “Method of Descaling Metallic Devices,” the entirety of which is herein incorporated by reference.
After having been polished, generally the stents are ready for use and mounted on their respective delivery systems. If it is desired, the stents may be coated with a beneficial agent for release within a vessel or artery after delivery of the endoprosthesis therein. If the stent is to be coated with a coating such as a beneficial agent this is generally done before the stent is mounted onto a delivery system.
There are various methods for applying a coating to an endoprosthesis. The most common method is to mount the endoprosthesis on a mandrel and spray a coating onto the surface of the endoprosthesis. It is preferred that all surfaces of the endoprosthesis are covered, through this is often difficult because the mandrel used to hold the endoprosthesis results in a discontinuity in the surface coating which could lead to coating failure or having the coating flake off the endoprosthesis upon delivery.
Typically when a stent has a coating applied to it, the stent must be tracked during the manufacturing process for regulatory reasons. This tracking may be performed by using numbered vials to hold the stent, or a numbered board to hold the mandrels. As production numbers increase it may become difficult to properly track each individual stent during the manufacturing process, therefore there is a need for an improved method and/or device for tracking a stent during production. There is also a need for improved mandrel designs to retain an endoprosthesis during manufacturing and coating. The present invention satisfies these and other needs.